All children with thyroid disorder attending the endocrinology clinic of the Ethio-Swedish Children's Hospital (ESCH), Addis Ababa in 1996 were included in this study. One hundred twenty six new patients from all over the country were referred to the clinic for thyroid disorder and 31 patients (24%) were found to have hypothyroidism. Seventeen (13%) had congenital hypothyroidism while the rest 14(11.5%) were categorised to have juvenile hypothyroidism. Thyroid dysgenesis is the commonest cause of permanent hypothyroidism. Mental retardation was the accompanied manifestation in all the cases with thyroid agenesis except in two children. Mental retardation being the commonest permanent sequelae in aplastic hypothyroidism is of utmost concern and its prevention is desirable, therefore high index of clinical suspicion with a close observation for early feature of congenital hypothyroidism is warranted for early intervention and in the future nation wide screening for hypothyroidism is recommended.